//
you're reading...

Biology

Whale Watching: Fun for Us, Stressful for Them

Paper

Christiansen, F.; Rasmussen, M. .; Lusseau, D. Inferring energy expenditure from respiration rates in minke whales to measure the effects of whale watching boat interactions. Journal of Experimental Marine Biology and Ecology. 2014. DOI: 10.1016/j.jembe.2014.05.014 (http://www.sciencedirect.com/science/article/pii/S0022098114001336)

Background

The experience of seeing a humpback whale breach is a common one around New England, thanks to the proliferation of whale watching tours in the past few decades.  Getting the chance to observe these majestic animals in their natural habitat is a treat for both locals and tourists alike. However, what we are seeing may not be the whale’s natural behavior – studies have shown that whales are affected by the presence of these whale watch boats, and being around them can have long-term negative consequences on whale health.

Because all animals need energy to survive, scientists often study how much energy (or oxygen) a particular task consumes under different conditions.  Usually when an animal is stressed or uncomfortable, the energy it needs and the oxygen it requires are both higher than normal.  The researchers in this study were interested in how whale watching boats affect the energy consumption of minke whales, a smaller whale species common in New England. To understand the energy consumption, they observed two main aspects of the whale’s behavior – the respiration rate and the swimming speed.

Breaching minke whale.

Breaching minke whale.

To fully understand how those two things are connected to each other and to energy consumption, think about what happens to your body when you’re swimming. You’re expending energy to swim and you’re replacing that energy by breathing more.  Whales are the same way – the researchers were able to estimate how much energy a whale uses by observing their respiration rate in conjunction with their swimming speed.

Methods

The researchers, based in Iceland, conducted their research both from a lighthouse platform on shore (control, whales not being followed by whale watch boats) and from commercial whale watching boats over two years.  From either the boat or from shore, they chose one whale and followed it as long as they could, recording when the whale surfaced (when the whale was breathing), how often the whale surfaced, and the GPS coordinates of each surface point. That allowed them to calculate how fast the whale was traveling and how many times the whale breathed in a given period of time.

From there, they could calculate the respiration rate, which was the total length of time that they followed the whale divided by the number of times the whale surfaced to breathe. Swimming speed was calculated in a similar fashion – the distance the whale swam (calculated from the GPS points) divided by the total length of time they followed the whale.

The researchers also took every step to make sure the data from their observations was valid.  They removed any observations that included a whale feeding because foraging behavior will impact the respiration rate.  They also made sure to rule out any observations that only considered a short amount of time so that they weren’t overestimating the respiration rate.  Finally, they even took out all the observations that took place when the seas were rough, which ensures that they didn’t somehow miss any time the whale surfaced to breathe. All that made sure that the researchers only included the most relevant observations in their calculations.

Armed with their observations and the calculated respiration rate and swimming speed, the researchers were able to do a number of calculations to determine the total metabolic rate and cost of transport.  The total metabolic rate of an animal is how much energy it consumes, which can be estimated by converting the respiration rate (in units of oxygen consumed per unit of time) to units of energy, like calories.  The cost of transport for an animal is how much energy it takes for the animal to move 1 kg of mass (2.2 lbs) one meter (3 ft).  Cost of transport for marine animals takes into account drag forces as well, so a fast-swimming animal can have a lower cost of transport than a slower swimming animal as long as it has a streamlined body shape.

Results

The researchers found that the whale watch boats do affect these minke whales – their average swimming speed was 1.02 meters/second (2.28 mph) faster when the boat was following them, which corresponds to an increase of 63%.  If you were being followed by a boat (or a shark!), you’d probably swim 63% faster, too!

Control animals were not being followed by boats, impact animals were.

Control animals were not being followed by boats, impact animals were.

The whales’ breathing rate was also affected by the presence of whale watch boats. The whales increased their breathing rates from 0.88 breaths/min to 1.12 breaths/min. While that might not sound like a large difference, it translates to a 27.6% increase in the amount of energy the whale has to use to do the same activity.

Control animals were not being followed by a whale watch boat, while impact whales were.

Control animals were not being followed by a whale watch boat, while impact whales were.

That 27.6% increase in energy expense is mostly caused by respiration, not by swimming speed – the whales are swimming faster, but because the cost of transport declines with swimming speed, the process that requires more energy from the whales is surfacing to breathe.  Because of drag forces, whales can swim underwater much more efficiently when they don’t have to come up to breathe – it’s the surfacing itself that increases the energy uptake.

Significance

One of the exciting finds of this study is that observation is a tool sensitive enough to study these minke whales. Of course, whales are highly endangered, sensitive, and large creatures, all of which prevent studying these animals under controlled laboratory conditions.  Getting reliable data just via field observation is a great find – not only is it mostly non-invasive to the animal, but it’s also a reasonably priced alternative for researchers to learn more about these species.

This study shows that our whale watching boats are having at least a small negative impact on minke whales – in the presence of boats, they get stressed and they must expend more energy to perform the same routine task of swimming.  Previous studies have shown that the whales are seeing the boat, and that’s how they’re aware of it, but because boats make a lot of noise, the whales may also be hearing the boat.

The increase in swimming speed closely mirrors previously measured swimming rates at a time when the whales were being chased by their primary predator, the killer whale. That suggests that these whales are viewing the whale watching boat as a predator, causing the increase in swimming speed, respiration rate, and energy consumption.

Some boats can be scarier than others!

Some boats can be scarier than others!

Whale watching boats can be great tools for education, but this study shows us that the very animals we’re trying to learn about and protect may be harmed by these tours.  We’ll have to carefully monitor this behavior in other species of whale so that we can make informed decisions on how often whale watching boats can take out passengers in the future.

Discussion

No comments yet.

Post a Comment

Instagram

  • by oceanbites 2 weeks ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 1 month ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 3 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 3 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 3 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 4 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 4 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 4 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 5 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 6 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 6 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 7 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 7 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 8 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 8 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 9 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
  • by oceanbites 9 months ago
    Feeling a bit flattened by the week? So are these summer flounder larvae. Fun fact: flounder larvae start out with their eyes set like normal fish, but as they grow one of their eyes migrates to meet the other and
WP2Social Auto Publish Powered By : XYZScripts.com